Travelling grate machine with drive



July 25, 1967 5, M COULTER ET AL 3,332,674

TRAVELLING GRATE MACHINE WITH DRIVE Filed Aug. 16, 1965 4 Sheets-Sheet lINVENTOR. STANLEY M.COULTER LEONARD J. BACHMAN BY (M MI their ATTORNEYSJuly 25, 1967 5 COULTER ET AL 3,332,674

TRAVELLING CRATE MACHINE WITH DRIVE Filed Aug. 16, 1965 4 Sheets-SheetINVENTOR. STANLEY M COULTER LEONARD J. BACHMAN #heir ATTORNEYS July 25.1 67 s. M. COULTER ET AL 3,332,674

TRAVELLING GRATE MACHINE WITH DRIVE Filed Aug. 16, 1965 4 Sheets-Sheet 3INVENTORS. STANLEY M.COULTER LEONARD J. BACHMAN July 25, 1967 5, CQULTERET AL 3,332,674

TRAVELLING GRATE MACHINE WITH DRIVE Filed Aug. 16, 1965 4 Sheets-Sheet 4L //3O \lk I F |g.5. u I

INVENTOR. f flk fifibfi l F|g.6. I BY their ATTORNEYS United StatesPatent 3,332,674 TRAVELLING GRATE MACHINE WITH DRIVE Stanley M. Coulter,Ben Avon, and Leonard J. Bachman,

Coraopolis, Pa., assignors to Dravo Corporation, Pittsburgh, Pa., acorporation of Pennsylvania Filed Aug. 16, 1965, Ser. No. 479,769 7Claims. (Cl. 266--21) This invention relates to travelling gratemachines such as are used in the sintering and pelletizing of iron ore,and particularly to the driving mechanism for such a machine.

In travelling grate machines of the type to which the present inventionrelates, a succession of separate pallets move in a generally horizontalpath from a charging end to a discharge end over a series of windboxes.At the discharge end the pallets are carried by a sprocket wheel to areturn track along which they travel to the charging end. In movingaround the sprocket at the discharge end, the charge in the pallets isdumped. At the charging end the pallets are raised by a power-drivensprocket to the upper strand. As each pallet in turn moves into place atthe starting or charging end, it pushes the line or strand of abuttingpallets ahead of it to the discharge end and the pallets being pushedfrom the discharge end power the sprockets that dump and lower them tothe return strand. While the pallets have flanged wheels that roll onrails and support most of the weight, each pallet has at least one sealat each end that rides on a sealing strip so that air or gases will flowto and from the several windboxes through the pallets and the chargecontained thereon. As a result of the length of the machine, the weightof the charge, the difliculty of providing lubrication both because ofheat and dust, the contact forces generated between the pallets movinginto position .at the charging end of the strand and pushing the palletson the strand ahead is enormous. Consequently, a very great strain isimposed on the driving mechanism through which the sprockets arerotated. There is generally provided a gear wheel on the sprocket wheelshaft, and this shaft is journaled in the head frame of the machine. Amotor and reduction gear train rotate this gear, and these mechanismsare supported usually independently of the head frame, but in the samebuilding structure as the head frame. This results in the problem ofmaintaining proper alignment and relation of the driving pinion and thedrive gear which in engages.

The present invention has for its principal object to provide a drivewhich will eliminate the problems of alignment as heretoforeencountered, and which will also distribute the driving forces so thatthey are not concentrated on a single tooth of the driving gear ordriving pinion.

This is accomplished by suspending a beam-like rigid frame from thedrive shaft for the sprockets, which shaft carries the main drivinggear, from hearings in which the shaft rotates. A driving motor,reduction gear, and pinions for engaging the main driving gear wheel ateach end of the rigid frame, the driving pinions of the two units beingdiametrically opposite.

The invention and its further objects and advantages will be more fullyunderstood by those skilled in the art by reference to the followingdetailed description of a machine embodying our invention in conjunctionwith the accompanying drawings.

In the drawings:

FIG. 1 is a fragmentary side elevation of the charging end of atravelling grate machine showing the head frame, drive shaft, and aportion of the track, parts being broken away to show a portion of thesprocket wheel and a portion of the drive wheel with the drivingmechanism not shown;

3,332,674 Patented July 25, 1967 FIG. 2 is a transverse section in theplane of line II II of FIG. 1, but with the drive gear being also shown;

FIG. 3 is a side elevation of the drive gear housing and the drive gearassembly;

FIG. 4 is a top plan view of the drive shown in FIG. 3;

FIG. 5 is a fragmentary section in the line VV of FIG. 3; and

FIG. 6 is a similar fragmentary view in the plane of line VI--VI of FIG.4.

Referring first to FIGS. 1 and 2, 2 designates the top rails of atravelling grate machine along which the pallets 3 are moved in thedirection of the arrow, and 4 are the bottom rails along which thepallets move in the'reverse direction and in inverted position towardthe lifting sprockets 5 at the charging end. The lifting sprockets raisethe pallets from the lower level to the upper one, turning them again tothe upright position as they elevate the pallets. There are two of thesesprockets, one at each side of the machine, and they are both fast on acommon shaft 6 mounted in bearings 7 in a rigid structural steel frame,designated generally as 8, and herein sometimes referred to as the headframe. This much of the machine is not substantially different fromother travelling grate machines, the pallets themselves having the usualgrate arrangement in the bottom.

According to the present invention, one end of the shaft projects at oneside well beyond the head frame, and has a drive gear wheel 10 keyedthereto. This gear wheel preferably has two sets of teeth 11 on itsperiphery disposed angularly to each other in herringbone fashion. Thereare two bearing assemblies on the projecting end of the shaft, one ateach side of the drive gear wheel 10, one of these, designated 12, beingat one side of the gear wheel and one, designated-13, at the other.These bearings are fixed to the top of a drive frame 14 comprised of twoparallel I-beams 15 extending horizontally below the shaft at rightangles thereto, the frame extending roughly about the same distance eachfrom the bearings 12 and 13 laterally beyond the periphery of the drivegear wheel 10. There is a housing or enclosure 16 secured to the top ofthe frame over and around the drive gear, and there is an enclosed oilpan 17 secured to the under side of the frame enclosing the lowerportion of the drive gear.

On each end of the drive frame is a motor 20, the drive shaft 21 ofwhich is coupled to a reducing gear schematically indicated at 22, whichdrives a sleeve 23 that is coupled at 24 to a pinion shaft 25 on whichare two pinions 26 that mesh with the herringbone teeth of the drivegear. The motors, reduction gears and pinions are matched in size,weight and power so that they are substantially in balance with eachother. The reducing gears, as seen in FIG. 6 are offset to one side ofthe longitudinal center of the frame so that the pinions 26 are in linewith the drive gear 10. The weight of the drive unit comprising themotor and reducing gear at each end of the beamlike drive framecounterbalance each other, and an extension 27 at one end of the driveframe is secured to a flexible cable 28 that is anchored at oppositeends, not shown, to the head frame structure or some other fixedlocations to hold the drive frame from rotating about the main driveshaft on which the sprocket wheels are fixed. A flexible cable is usedbecause it will not transmit any stresses on the beam-like framesideways or endwise due to any relative movement of the head frame inthe building or to the drive shaft.

By having the drive units on the frame suspended by the sprocket wheelshaft, the relation of the drive to the driving gear is fixed and cannotbe affected by relative expansion and contraction under thermal changesor by stresses such as have heretofore caused alignment difl'lculties.By using two motors and two reducing gears, the

stresses on the gear teeth are divided and applied to the driving gearat diametrically opposite locations, and at the same time. the suspendeddriving beam is balanced. The frame itself is below the axis of thedrive gear so that the centers of the pinions 26 are on a diameter ofthe driving gear, and the center of gravity of the frame is below theaxis of the shaft. Further stability is provided by a counterweight 30under each end of the beam, one being about equal to the other. Thesefurther lower the center of gravity and increase the inertia of thedriving frame, and while the reduction gears are offset to one side ofthe frame, these weights, as shown in FIG. 6, are offset to one side ofthe frame, thereby tending to equalize the overturning momentum aboutthe axis of the driving frame. The herringbone teeth on the pinions 26and drive gear tend to equalize end thrust on the shaft 25, furthereliminating alignment problems.

The invention may be modified as to the particular construction of partswithin the contemplation of our invention and under the scope of thefollowing claims.

We claim:

1. In a travelling grate machine having upper and lower tracks alongwhich a succession of pallets are moved and a pair of sprocket wheels atone end for elevating pallets from the lower track to the upper one,said sprocket wheels being fixed on a drive shaft having a drive gearwheel at one end, with a frame in which said shaft is journaled, theinvention comprising a drive for the drive shaft, said drive comprising:

a rigid beam-like frame,

bearings on said beam-like frame in which the drive shaft is rotatableand by which the frame is hung from the shaft below the axis of theshaft,

a drive motor at each end of the beam-like frame,

a reduction gear on each end of thebeam-like frame,

each driven by one of said motors,

a pinion shaft driven by each reduction gear, each pinion shaft having apinion thereon meshing with said drive gear wheel for rotating saidwheel,

and means for restraining said beam-like frame against the free rotationabout the drive shaft.

2. A travelling grate machine as defined in claim 1 wherein saidlast-named means is a flexible cable attached to one end of thebeam-like frame with its opposite ends anchored at fixed points, saidfiexible cable restraining the frame against rotation but beingincapable of transmitting any pull on the beam-like frame sideways or inthe direction of its length. 1

3. A travelling grate machine as defined in claim 1 in which the centersof the pinion shafts at opposite'ends of 4 the frame are diametricallyopposite the center of said drive shaft.

4. A travelling grate machine as defined in claim 1 in which the centersof the pinion shafts at opposite ends of the frame are diametricallyopposite the center of said drive shaft, said motors, reduction gearsand pinions being of the same size and weight.

5. A travelling grate machine as defined in claim 1 in which the centersof the pinion shafts at opposite ends of the frame are diametricallyopposite the center of said drive shaft, said motors, reduction gearsand pinions being of the same size and weight, the reduction gears beingto one side of the drive gear wheel and the longitudinal axis of thebeam-like frame, and a counterweight under the beam-like frame adjacenteach end thereof to lower the center of gravity of the beam-like frameand stabilize it and balance the opposite ends of the beam-like frame.

6. A travelling grate machine as defined in claim 1 in which the centersof the pinion shafts at opposite ends of the frame are diametricallyopposite the center of said drive shaft, said motors, reduction gearsand pinions being of the same size and Weight, the reduction gears beingto one side of the drive gear wheel and the longitudinal axis of thebeam-like frame, and a counterweight under the beam-like frame adjacenteach end thereof to lower the center of gravity of the beam-like frameand stabilize it and balance the opposite ends of the beam-like frame,the counterweights being offset to the side of the axis of the beam-likeframe opposite the side on which the reduction gears are offset toequalize the overturning momentum about the axis of the frame.

7. A travelling grate structure as defined in claim 1 in i which thedrive gear wheel has herringbone teeth and the pinions that meshtherewith have corresponding teeth.

References Cited UNITED STATES PATENTS 1,495,930 5/1924 Sing 74-665 X1,617,561 2/ 1927 Alexovits 26621 2,518,781 8/1950 Hindmarch' 746612,670,947 3/1954 Duncan 2662l 2,745,659 5/1956 Osojnak 266-21 2,915,16712/1959 Berger 198-127 2,997,608 8/1961 Musser 198-127 X 3,141,5447/1964 Hansen 266-21 X 3,213,711 10/1965 Kieboom 74-661 X J. SPENCEROVERHOLSER, Primary Examiner. V

R. S. ANNEAR, Assistant Examiner.

1. IN A TRAVELLING GRATE MACHINE HAVING UPPER AND LOWER TRACKS ALONGWHICH A SUCCESSION OF PALLETS ARE MOVED AND A PAIR OF SPROCKET WHEELS ATONE END FOR ELEVATING PALLETS FROM THE LOWER TRACK TO THE UPPER ONE,SAID SPROCKET WHEELS BEING FIXED ON A DRIVE SHAFT HAVING A DRIVE GEARWHEEL AT ONE END, WITH A FRAME IN WHICH SAID SHAFT IS JOURNALED, THEINVENTION COMPRISING A DRIVE FOR THE DRIVE SHAFT, SAID DRIVE COMPRISING:A RIGID BEAM-LIKE FRAME, BEARINGS ON SAID BEAM-LIKE FRAME IN WHICH THEDRIVE SHAFT IS ROTATABLE AND BY WHICH THE FRAME IS HUNG FROM THE SHAFTBELOW THE AXIS OF THE SHAFT, A DRIVE MOTOR AT EACH END OF THE BEAM-LIKEFRAME,